Active control of friction between sliding surfaces is of significant interest in automotive applications. It has been shown that the friction force between sliding surfaces can be reduced by superimposing ultrasonic vibrations on the sliding velocity. This principle can be applied to systems in which solid state lubrication is advantageous. This paper investigates ultrasonic lubrication for creating adaptive seat belts with controllable force at the interface between the D-ring and webbing. By precisely controlling the seat belt force during a crash event, superior restraint can be achieved relative to existing systems which are designed as a compromise for various occupants and loading conditions. Proof-of-concept experiments are conducted in order to experimentally determine the performance limits and mechanics of a seat belt webbing subjected to macroscopic sliding motion and superimposed out-of-plane ultrasonic vibrations. The experimental setup consists of a high-capacity ultrasonic plastic welder and an apparatus for creating controlled relative motion between the welder tip and seat belt webbing. Analytical modeling using LuGre friction is presented which characterizes the parametric dependence of friction reduction on system settings in the presence of ultrasonic vibrations.
Active control of friction between sliding surfaces is of fundamental and practical interest in automotive applications. It has been shown that the friction force between sliding surfaces decreases when ultrasonic vibration is superimposed on the sliding motion. This principle can be applied to systems in which solid state lubrication or friction modulation is advantageous. The ultrasonic vibration may be applied longitudinally or normal to the direction of motion. A number of friction models have been considered in order to analyse this phenomenon. The degree of friction reduction has been shown to depend on the ratio of the sliding velocity to the vibration velocity. Since friction is a system response, it is necessary to include system dynamics in the analysis of ultrasonic lubrication. A nonlinear single-degree-offreedom-model is formulated and numerically approximated to quantify the effect on friction reduction of control force, intrinsic coefficient of friction, mass load, tangential contact stiffness at the sliding interface, and system stiffness. Model results are in close agreement with experimental measurements.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.